Pressure sensitive adhesive (PSA) compositions are used in a wide variety of applications. Numerous applications require pressure sensitive adhesives to support a load at elevated temperatures, typically in the range of greater than 70° C., for which high cohesive strength PSAs are required. A standard method of increasing cohesive strength at elevated temperatures is to chemically crosslink the PSA using irradiation processes, such as thermal radiation, ultraviolet (UV) radiation, gamma radiation, and electron beam (EB) radiation, etc. Although these processes improve cohesive strength, they often negatively impact other properties, including peel strength of the PSA.
PSA compositions have been used as tapes, in particular as double-sided tapes used to adhere two articles together. Such double-sided PSA tapes are useful, for example, in automotive manufacturing, numerous consumer products, construction, and for maintenance and repair of many items. Most conventional double-sided PSA tapes typically require that at least one side of the tape be covered with a release liner to prevent the two sides from sticking together. Although such release liners are functional, they have the disadvantage of being time consuming to use, as well as adding expense to the PSA tape and waste to its application.
For some applications, PSAs formed into foams are desirable because tapes made of foam can conform better to certain substrates, thereby giving better adhesion and greater holding power. Foamed PSA tapes are particularly desirable on irregular shaped surfaces that would not otherwise provide an adequate surface with which to contact the PSA.
Therefore, a need exists for an improved PSA tape that does not require irradiation, and which advantageously can be produced without the use of a release liner on one or both major surfaces, and which includes a foam to improve adhesion to irregular surfaces.